High Density Lipoprotein Level is Negatively Associated With the Increase of Oxidized Low Density Lipoprotein Lipids After a Fatty Meal

Recent reports show that a fatty meal can substantially increase the concentration of oxidized lipids in low density lipoprotein (LDL). Knowing the LDL‐specific antioxidant effects of high density lipoprotein (HDL), we aimed to investigate whether HDL can modify the postprandial oxidative stress after a fatty meal. Subjects of the study (n = 71) consumed a test meal (a standard hamburger meal) rich in lipid peroxides, and blood samples were taken before, 120, 240, and 360 min after the meal. The study subjects were divided into four subgroups according to the pre‐meal HDL cholesterol value (HDL subgroup 1, 0.66–0.91; subgroup 2, 0.93–1.13; subgroup 3, 1.16–1.35; subgroup 4, 1.40–2.65 mmol/L). The test meal induced a marked postprandial increase in the concentration of oxidized LDL lipids in all four subgroups. The pre‐meal HDL level was associated with the extent of the postprandial rise in oxidized LDL lipids. From baseline to 6 h after the meal, the concentration of ox‐LDL increased by 48, 31, 24, and 16 % in the HDL subgroup 1, 2, 3, and 4, respectively, and the increase was higher in subgroup 1 compared to subgroup 3 (p = 0.028) and subgroup 4 (p = 0.0081), respectively. The pre‐meal HDL correlated with both the amount and the rate of increase of oxidized LDL lipids. Results of the present study show that HDL is associated with the postprandial appearance of lipid peroxides in LDL. It is therefore likely that the sequestration and transport of atherogenic lipid peroxides is another significant mechanism contributing to cardioprotection by HDL.     

Shell煤气变换高水气比改低水气比工艺总结

Shell炉制得的粗煤气CO含量高,变换采用高水气比工艺虽然无甲烷化副反应,但蒸汽消耗高。河南开祥化工有限公司的应用实践证明:选用低水气比耐硫变换工艺可以获得很好的效果。     

焙烧对铝土矿尾矿相转变,失重率及平均粒径与比表面积的影响

本文对铝土矿尾矿以不同温度进行焙烧,采用X射线衍射分析、差热-热重分析、平均粒径与比表面积分析等分析手段详细表征了焙烧温度对铝土矿尾矿主要矿物的矿相转变,尾矿的失重率及平均粒径与比表面积的影响.结果表明尾矿中的一水硬铝石及高岭石在600℃以前完全分解,分别转化为刚玉相及偏高岭石相;伊利石在500℃以上开始脱水生成脱水伊利石相;石英相、赤铁矿相与锐钛矿相基本无明显变化;由于一水硬铝石及高岭石在400～600℃之间完全脱除结构水,尾矿在此温度区间剧烈失重8.4％左右;随焙烧温度的提高,铝硅酸盐矿物逐步脱水分解导致尾矿的平均粒逐渐减小,比表面积逐步增大;但高于800℃以上,在脱水伊利石相与赤铁矿相接触面处,由于K2O-SiO2-Al2O3-Fe2O3四元系低熔点化合物的生成,尾矿颗粒产生粘结,导致尾矿的平均粒径转而上升,比表面积转而下降.     

Effect of Polymethyl Methacrylate (PMMA) Powder to Liquid Monomer (P/L) Ratio and Powder Molecular Weight on the Properties of PMMA Cement

The present study investigated the effect of PMMA powder to liquid monomer (P/L) ratio and molecular weight of PMMA powder on the properties of PMMA cement. Two types of PMMA powder (Mw: 120,000 and 350,000) were prepared with different P/L ratios (based on wt/wt ratios); 0.75:1, 1:1, 1.25:1, and 1.5:1. Characterization of PMMA powders, handling characteristics and flexural properties of cured PMMA samples were investigated. In conclusion, low P/L ratio and high molecular weight of PMMA powders are desirable to produce PMMA cement with good handling properties and high flexural properties.     

不同硅铝比HZSM-5分子筛的甲醇制芳烃性能

采用固定床反应器,以甲醇为原料,在反应温度为430℃和反应空速为2 h-1的条件下,考察了不同硅铝比HZSM-5分子筛催化剂的甲醇制芳烃反应(MTA)性能,并采用X射线衍射(XRD)、氨气程序升温脱附(NH3-TPD)、物理吸附、傅立叶红外光谱(FT-IR)等技术对催化剂进行了表征。结果表明:MTA反应是强酸主导的催化反应,随着分子筛硅铝比的降低,分子筛总酸量逐渐增加,强酸相对总量逐渐提高,其中弱酸相对总量降低。这主要是由于分子筛中Al含量逐渐上升,作为强酸位的Si-OH-Al逐渐增加所致,催化剂反应活性与之呈正向相关的关系。当HZSM-5催化剂中的强弱酸总量比由0.3增加到0.6时,苯-甲苯-二甲苯(BTX)的选择性由36%增至64%,说明催化剂的活性显著提高;当强弱酸总量比由1.1增至1.5时,BTX选择性变化仅为0.92%,催化性能提升不明显,HZSM-5分子筛的MTA反应性能与其硅铝比呈反向相关关系。     

L—1型低汽气比低变催化剂的研制

L-1型低汽气比低变催化剂具有低汽气比条件下活性高、选择性好及堆密度低的特点,其性能已达到国内领先和国际先进的技术水平,具有广阔的市场应用前景。     

小长径比药盘钢模压制成型工艺研究

通过对炸药压装成型过程的深入分析，揭示了钢模压制小长径比药盘的技术关键是必须使所装填的散粒体炸药在压件的横断面上全面实现其质量的合理分配，设计定程式双向钢质压模，合理确定垫圈厚度和括药器结构。